1. Field of the Invention
The present invention relates to a method for controlling a library apparatus to automatically read barcode labels of recording medium such as magnetic tape cartridges stored in cells using a line scanning type reader installed in a medium carrier robot, a program and units. Especially, a method for controlling a library apparatus to efficiently handle the error caused by scanning the recording medium which is not affixed the barcode label, a program and units.
2. Description of the Related Arts
In conventional library apparatus, medium cartridges such as magnetic tape cartridges affixed the barcode labels are stored by cell in a plurality of storage cells provided in the housing. The medium cartridges are picked up by the carrier robot from the storage cells designated as the origin according to the move command from the host, conveyed to a drive module as the destination by the move command and put into the drive module so that the medium are recorded or reproduced. The recorded or reproduced medium cartridges are picked up by the carrier robot from the drive module designated as the origin according to the move command from the host and turned back to the storage cells designated as the destination according to the move command.
The medium cartridge is affixed the barcode label which is recorded medium control information on the back surface thereof when it is put into the library apparatus. The barcode label of the medium is read by a barcode reader installed in the carrier robot. The barcode reader is provided with a LED lighting unit in which LEDs are linearly arranged and a one-dimensional CCD. The barcode label is scanned by the one-dimensional CCD while the LED lighting unit is turn on thereby the barcode label can be read.
(Patent document 1)
Japanese Patent Application Laid-Open Publication No. 11-45306
(Patent document 2)
Japanese Patent Application Laid-Open Publication No. 2000-260089
In the library apparatus, an inventory operation to continuously read barcode labels of a number of medium cartridges stored in the apparatus and notify the host of the location and type of the medium cartridges when the necessary number of medium cartridges are put into the library apparatus and stored in the cells to start the operation. The minimum operation unit of the inventory operation is one column as a longitudinal line of the storage cells in a storage cabinet in the apparatus. That is to say, the inventory operation is performed such that the carrier robot is moved and positioned at the top of cell location in the column targeted for processing, then the carrier robot is moved up and down at a regular speed as the barcode reader is scanning to continuously read the barcode labels.
However, the medium cartridge which is not affixed the barcode label is sometimes stored in the library apparatus due to forget to affix the label or come off it. When such medium cartridge which is not affixed the barcode label is scanned by the barcode reader in the inventory operation, it can be not determined the cause of the error whether a barcode label is not affixed, the barcode label is fouling or the barcode reader is at fault by only the scanning data obtained as the reading result.
Therefore, in the conventional library apparatuses, in case of the error data is extracted from the reading result at the time the inventory operation for one column is completed, a diagnosis process is executed to determine which of a failure of the barcode reader or a defect of the barcode label is the cause of error. If it is no problem, the barcode label accounted for the error is subjected to the retry operation.
FIG. 22 is a flowchart of the conventional inventory process, which is following procedure:    Step S1: Designate a target column which is performed the inventory operation, and move to the carrier robot to the top cell of the target column and position thereto.    Step S2: Continuously read the barcode labels of the medium cartridges stored in the column by moving up and down the carrier robot as scanning by the barcode reader (inventory operation).    Step S3: Check the presence or absence of any error in the reading result. If there is any error, advance to a step S4, otherwise, the process is completed.    Step S4: If the diagnosis condition for the barcode reader that all of the plurality of scanning data for the same medium (three scanning data for each medium)are error data is fulfilled, advance to Step S5, otherwise advance to Step S6.    Step S5: Move the carrier robot to the medium cartridge to be error and position thereto, and execute a diagnosis process for the barcode reader.    Step S6: Move the carrier robot to the medium cartridge to be error and position thereto, and execute a retry process.
In the retry process, the label range of the medium cartridge is divided into three regions such as an upper section, a middle section and a lower section, and each region is subdivided into five steps of scanning position. The barcode reader repeatedly operates so called stop-scanning to read by exposing during a predetermined period while the barcode reader is fixedly positioned for each scanning position. The method using such retry process is useful for in the case that the barcode is fouling, however if a barcode label is not affixed to the medium cartridge, unnecessary retry operations are repeated the fixed times (for example, the stop-scanning operations are repeated the prescribed times such as fifteen times as the maximum number of times for retry)so that the process time is lengthened.